<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<form action="index.php?group=admin&module=privilege&action=checks" method="post">
		<p>username: <input type="text" name="username"></p>
		<p>password: <input type="password" name="password"></p>
		<p>验证码：<input type="text" name="captcha"></p>
		<p><img src="index.php?group=admin&module=privilege&action=captcha" alt="验证码" onclick="change()"></p>
		<p><input type="submit" value="提交"></p>
	</form>
</body>
<script>
	function change(){
		document.getElementsByTagName('img')[0].src = "index.php?group=admin&module=privilege&action=captcha&r="+Math.floor(Math.random()*10);
	}
</script>
</html>